Bus-bar mounting



Patented Dec. 1, 1942 BUS -BAR MOUNTING unt Lebanon, Pittsburgh,

John E. Huguelet, Mo

Pa., assignor to National Electric Products Corporation, a corporation of Delaware Application March 29, 1941, Serial No; 385,913

3 Claims.

This invention relates to a bus-bar mounting for inclusion in an electrical distribution system.

In electrical distribution systems bodies of electrical insulating material are used to contact the bus-bars, and to afford electrical protection in the assembly. In such systems it is desirable that the insulating members, or bodies, be so mounted that they are proof against the loosening effect of long-continued vibration, and that the bus-bar be so engaged to the insulating members that shifting of the bus-bars in the insulating members is prevented.

One object of my invention is to provide a particularly advantageous attachment of the insulating members to the structure in which the insulating members are mounted; both to facilitate the manufacture of the insulating members, and firmly to integrate the insulating members with the structures in which they are mounted against the loosening tendencies of vibration.

Another object of my invention is to provide simple and effective means organized to prevent shifting movement of the bus-bars in the insulating members which contact them.

In the accompanying drawing, exemplary of my invention,

Fig. I is a view partially in end elevation and partially in vertical section, showing the assembly of a bus-bar support of specialized form including insulating members mounted in accordance with my invention, and showing elements for positioning the bus-bars in the insulating members.

Fig. II is a cross-sectional view taken in the plane of section line IIII of Fig. I, showing in detail the structure for preventing shifting of the bus-bars in the insulating members which contact them.

Fig. III is an isometric detail view showing a fragmentary piece of one of the bus-bars with the element for positioning it with respect to insulating members attached to the bus-bar.

The bus-bar support exemplified by the drawing includes primarily the structure shown in my companion application Serial No. 385,911, filed March 29, 1941. As in the disclosure of that ap-- plication, the bus-bar support includes a metallic frame structure having two U-shaped frame elements 1 and 2, which are arranged with their side portions, or legs, presented toward each other, and which are adjustable toward and from each other on connector plates 3. Each of the connector plates 3 carries two spaced stud bolts 4, provided with nuts to for the attachment of housing elements to the support and for the attachment of the bus-bar support to mounting structures.

In the two opposed frame elements I and 2 there are mounted two insulating bus-bar contacting structures 5 and G, secured to the frame elements, and arranged in opposition to each other. These insulating structures 5 and 9 are shown as one-piece members, arranged cooperatively to contact three bus-bars I, which stand in opposed seats 8 in the insulating members. If desired, three individual insulating members may be mounted on each frame element in opposition to those on the other frame element. As shown, the bus-bars 'l consist each of one flat piece of conductive metal but may, if desired, consist, in accordance with common practice, of two flat conductors spaced slightly from each other in assembly.

Insulating members 5 and 6 are secured within frame elements I and 2 by means of screws 9. It has been previous practice, in providing insulating members for contacting the bus-bars of electrical distribution systems, to employ porcelain insulators having prepared recesses for the reception of screws or bolts. Such recesses have been prepared by securing in them sleeves or plugs of metal, fibrous material, or the like for engagement by the threads of an attaching screw; or to cement bolts in recesses provided in the insulating members, by means of sulphur, or other suitable cementing material.

I have discovered that by making the insulat ing members of electrical insulating material of suitable sort, and by using suitable means for attaching the insulating members to the structural elements in which they are mounted, I am able to make an assembly in which there is lessened probability that the insulating members may work loose from their mounting structures when the system in which they are included is subjected to long-continued vibration. In so doing, I use as the material of which the insulating members are made one of the known, and commercially available, moldable compositions, possessing properties of electrical insulation, which have also in measure the properties of toughness and machinability. I have discovered that a screw of the self-threading sort, can be inserted in an undersize hole, or recess in material of that sort, firmly to engage therein by the thread which the screw itself cuts during its insertion. In manufacture, I make the insulating members of one of the known varieties of composition above noted, typically using one of the known moldable insulating compositions composed of Portland cement and suitable fibrous material, such as as bestos fibre, jute, or the like; and which surprisingly I have found to be capable of receiving a thread cut by a self-threading screw.

In molding the insulating members, I form therein recesses 10 extended inwardly from the surface of the insulator, which in assembly lies away from the bus-bars I. These recesses, which desirably are circular in section, I make of a diameter less than the maximum thread diameter of the shanks 9a of screws 9, and use screws of the sort capable of cutting threads for themselves when inserted. In assembly, the insulating members and 6 are positioned in the elements of the frame structure with the mouths of recesses ID in register with holes i I through the backs of the frame elements. The screws 9 are then run down by suitable means, as by a screwdriving machine until their heads 9b lie against the outer surfaces of the frame elements. During this insertion the screws 9 cut threads for themselves in the threadable material of the insulating members, firmly to engage those members to the frame elements.

I have found that this attachment of the busbar contacting insulators secures them more firmly to the structural elements of the bus-bar support than any attachment previously used, enduringly to sustain continued vibration in mounted installation of the electrical distribution system of which the bus-bar support forms an element.

While, as above noted, I have discovered that insulating members of the sort composed of fiber and cement rather than of porcelain, are sufficiently tough to permit the cutting of threads therein, it is desirable that they should not be subjected to severe crushing forces. This is more urgently the case if the electrical insulating members he composed, as is usual, of porcelain or similar brittle material. In order definitely to position the bus-bar 1 in the electrically insulating members, without exerting clamping force on the bus-bars, I provide means which in the assembly prevent shifting movement of the bus-bars in the insulating members.

Such means consist of an H-shaped structure including a cross-bar l2 secured to a bus-bar in any suitable manner, as by a cotter pin I3, and side members l4 riveted or otherwise suitably secured to the cross-bar and spaced from each other a distance equal to the width of the insulating members. The length of the side members ll of the positioning structure, or spreader, is slightly greater than the width of the insulating members. With a bus-bar l in the opposed seats 8 of two insulating members, side members H of each of the positioning structures, or spreaders, extends a short distance along, and in contact with, both sides of each of the insulating members. In mounted position of the bus-bar, the side members of its spreader thus prevent shifting movement of the bus-bar in either direction longitudinally of the bus-bar. In order to increase the area of contact between the side members H of the spreaders and the insulating members, side members H are desirably L-shaped in cross section with one leg Ila of the L presented for contact with the insulating members.

The above described spreaders are useful in a.

bus-bar support, and in unit assemblies of a pin rality of bus-bar support and housing structure, such as is disclosed in my companion application Serial No. 385,912, filed March 29, 1941. In such unit assemblies the spreaders prevent injury to the bus-bars and their insulators by movement of the bus-bars during their handling and shipment prior to installation. They also preserve the desired relative positioning of unit lengths of the bus-bars, with their ends either in line or staggered in accordance with a predetermined arrangement, and thus prevent loss of electrically proper spacing in the endregions of the busbar units where interconnecting bolts and nuts are carried. The spreaders are of particular advantage if the bus-bar supports are so mounted that the bus-bars extend in a vertical direction, as in such mounted position of the assembly they serve to bind the bus-bars to the insulating members in the several bus-bar supports of the assembly, against the pull of gravity. In such position with its increased torsional stresses on the insulating members, firmly enduring connection between the insulating members and the frame of the bus-bar support is also of particular value.

It is to be understood that many changes in the form and arrangement of the parts of which the above described assembly is made, and the material of which they are composed, may be made without going beyond the bounds of my invention, and my invention is therefore to be limited in scope only by the bounds of the claims appended hereto.

I claim as my invention:

1. In a bus-bar support for inclusion in an electrical distribution system including a frame structure, the combination with insulators having therein bus-bar receiving seats mounted in the said frame structure with their bus-bar seats in aligned opposition, and bus-bars mounted in the opposed seats of the said insulators, of spreaders secured to the bus-bars and regionally embracing both insulators in which the bus-bars are mounted.

2. In a bus-bar support for inclusion in an electrical distribution system including a frame structure, the combination with insulators having therein bus-bar receiving seats mounted in the said frame structure with their bus-bar seats in aligned opposition, and bus-bars mounted in the opposed seats of the said insulators of H- shape spreaders having their cross bars secured each to a, bus-bar, and having their legs longer than the spacing between the insulators adjacent their aligned seats and embracingly extended along'the bodies of the insulators.

3. In a bus-bar support for inclusion in an electrical distribution system and including a frame structure, insulators having therein busbar receiving seats mounted in the said frame structure with their bus-bar seats in aligned opposition, and a bus-bar mounted in the opposed seats of the said insulators; a bus-bar positioning structure adapted for engagement to a bus-bar to lie at a face thereof and having portions adapted to extend in spaced relation transversely of and outwardly of an engaged bus-bar to embrace between them the structure of opposed insulators in which the bus-bar is mounted v JOHN E. HUGUELET. 

